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Characteristics of Design Parameters on the Regenerative Blower Used for Building Fuel Cell System (건물 연료전지용 재생블로어 설계변수 특성연구)

  • Jang, Choon-Man;Lee, Jong-Sung
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.24 no.10
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    • pp.739-744
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    • 2012
  • This paper describes the blower performance used for single-stage high pressure regenerative blower. The blower considered is widely applied to the field of a fuel cell system, a medical equipment and a sewage treatment plant. Flow rate and rotating frequency of a impeller of the blower are considered as design parameters for the proper operation of the blower. Three-dimensional Navier-Stokes equations are introduced to analyze the performance and internal flow of the blower. Relatively good agreement between experimental measurements and numerical simulation is obtained. Throughout a numerical simulation, it is found that small and stable vortical flow generated inside the blade passage is effective to increase pressure and efficiency of the blower. Large local recirculation flow having low velocity in the blade passage obstructs the generation of stable vortical flow, thus increases the pressure loss of the blower. Detailed flow field inside the blower is also analyzed and discussed.

Evaluation of Numerical Models for Analysing an Industrial Centrifugal Blower (산업용 원심블로어 수치해석을 위한 수치모델 평가)

  • Lee, Jongsung;Jang, Choonman
    • Journal of Hydrogen and New Energy
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    • v.23 no.6
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    • pp.688-695
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    • 2012
  • The present study represents the effects of boundary condition on the performance of a centrifugal blower at the interference plane between rotational and stationary domains using three dimensional compressible Navier-Stocks equations. Two boundary conditions, frozen-rotor and stage, are compared to analyze the blower performance. Installation angle between the cutoff of a volute casing and a impeller blade is also introduced to evaluate the blower performance and to understand the internal flow inside the blower. Throughout numerical simulation, it is found that the frozen rotor interface method at the interference plane represents well the variations of flow field inside the blower compared to stage interface method. However, pressure has maximum two percent error according to the installation angles while pressure is almost constant for the stage interface method. And stage interface method can relatively well predict the blower performance. Detailed internal flows of the centrifugal blower are compared and analyzed by numerical simulation.

Evaluation of Inflow Uniformity on the Performance of Double-Inlet Centrifugal Blower Using Optimal Design Method (양흡입 원심블로어 성능향상을 위한 입구 유동 최적화 연구)

  • Lee, Jong-Sung;Jang, Choon-Man;Jeon, Hyun-Jun
    • Journal of Hydrogen and New Energy
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    • v.24 no.4
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    • pp.326-333
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    • 2013
  • This paper presents the performance enhancement of a double-inlet centrifugal blower by the shape optimization of an inlet duct. Two design variables, a length of anti circulation vane and an angles of inlet guide, are introduced to improve the inlet flow uniformity leading to the blower performance. Three-dimensional Navier-Stokes equations are used to analyze the blower performance and the internal flow of the blower. From the shape optimization of the inlet duct of the double-inlet centrifugal blower, the optimal positions of each design variable are determined. Throughout the analysis of sensitivity, it is found that the angle of the inlet guide is more effective than the length of the anti-circulation vane to increase flow uniformity at the outlet of the duct. Efficiency and pressure for the optimal inlet duct shape are successfully increased up to 3.55% and 3.2% compared to those of reference blower at the design flow condition, respectively. Detailed flow field inside the blower is also analyzed and compared.

Performance Comparison Evaluation of a Regenerative Pump with S-Shaped Continuous Impeller ('S' 형상의 연속형 임펠러를 갖는 재생형 펌프의 성능 비교평가)

  • JEON, SEOK-YUN;LEE, SANG-MOON;YOON, JOON-YONG;JANG, CHOON-MAN
    • Journal of Hydrogen and New Energy
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    • v.29 no.2
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    • pp.205-211
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    • 2018
  • Performance evaluation of a regenerative pump has been compared with a conventional open channel impeller and a S-shaped continuous impeller designed newly. To analyze flow field for both pumps, analysis code, CFX, is employed. Unstructured grids are used to represent a composite geometryincluding blade, casing and ducts. Throughout the comparisons between numerical simulation and experiments, the predicted efficiency has a good agreement with the experimental one. It is noted that the pump having a S-shaped continuous impeller is about 4.8 percent more efficient than conventional one, which is due to the relatively large pressure increase. Detailed flow field inside the pump is also analyzed and compared.

Numerical Evaluation of Flow Nature at the Downstream of a Ball Valve Used for Gas Pipelines with Valve Opening Rates (개도율에 따른 가스파이프라인용 볼 밸브 후류유동의 수치평가)

  • KIM, CHUL-KYU;LEE, SANG-MOON;JANG, CHOON-MAN
    • Journal of Hydrogen and New Energy
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    • v.29 no.4
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    • pp.370-377
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    • 2018
  • Ball valve has been widely used in the field of high-pressure gas pipeline as an important component because of its low flow resistance and good leakage performance. The present paper focuses on the flow nature at the downstream of the ball valve used for gas pipelines according to valve opening rates. Steady 3-D RANS equations, SC/Tetra, have been introduced to analyze the flow characteristics inside the ball valve. Numerical boundary conditions at the inlet and outlet of the valve system are imposed by mass flow-rate and pressure, respectively. Velocity distributions obtained by numerical simulation are compared with respect to the valve opening rates of 30, 50, and 70%. Cavity distributions, asymmetry flow velocity and the flow stabilization point at each opening rate are also compared. When the valve opening rates are 30 and 50%, the flow stabilization requires the sufficient length of 10D or more due to the influence of the recirculation flow at the downstream of the valve.

Pressure Drop in a Circular Pipe of Waste Collection Piping System (쓰레기 관로 이송 시스템의 관로 압력강하 평가)

  • Jang, Choon-Man;Lee, Sang-Yun;Suh, Sang-Ho
    • The KSFM Journal of Fluid Machinery
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    • v.10 no.4
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    • pp.55-60
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    • 2007
  • This paper describes an evaluation method of pressure drop in a circular pipe of waste collection piping system. Accurate pressure drop in a piping system is very important to determine the capacity of turbo blower, which is one of the main elements in the system. Three-dimensional Navier-Stokes analysis is introduced to analyze the pressure drop in the piping system. Organic waste is selected and modeled using the result of site survey performed in an apartment area. Evaluation method of pressure drop used In the present numerical simulation is performed in the shortened pipe line prior to the calculation of the real system. Throughout the numerical simulation, pressure drop in a waste pipe is obtained and compared to the value determined by analytical method. The pressure drop obtained by numerical simulation has a good agreement with that of the analytic method. It is noted that present evaluation method is effective to determine a pressure drop in the piping system. Detailed flow characteristics inside the pipe line are also analyzed and discussed.

Shape Optimization of a Stator Blade in a Single-Stage Transonic Axial Compressor (단단 천음속 축류압축기의 정익형상 최적설계)

  • Kim Kwang Yong;Jang Choon Man
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.29 no.5 s.236
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    • pp.625-632
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    • 2005
  • This paper describes the shape optimization of a stator blade in a single-stage transonic axial compressor. The blade optimization has been performed using response surface method and three-dimensional Navier-Stokes analysis. Two shape variables of the stator blade, which are used to define a stacking line, are introduced to increase an adiabatic efficiency. Data points for response evaluations have been selected by D-optimal design, and linear programming method has been used for an optimization on a response surface. Throughout the shape optimization of a stator blade, the adiabatic efficiency is increased to 5.8 percent compared to that of the reference shape of the stator. The increase of the efficiency is mainly caused by the pressure enhancement in the stator blade. Flow separation on the blade suction surface of the stator is also improved by optimizing the stator blade. It is noted that the optimization of the stator blade is also useful method to increase the adiabatic efficiency in the axial compressor as well as the optimization of a rotor blade, which is widely used now.

Frequency Characteristics of Fluctuating Velocity According to Flow Rates in a Tip Leakage Vortex and a Wake Flow in an Axial Flow Fan (축류 홴의 익단누설와류 및 후류에서 유량에 따른 변동속도의 주파수 특성)

  • Jang, Choon-Man;Kim, Kwang-Yong;Fukano, Tohru
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.28 no.2
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    • pp.181-188
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    • 2004
  • The frequency characteristics in an axial flow fan operating at a design and three off-design operating conditions have been investigated by measuring the velocity fluctuation of a tip leakage vortex and a wake flow. Two hot-wire probe sensors rotating with the fan rotor. a fixed and a moving ones, were introduced to obtain a cross-correlation coefficient between two sensors as well as the fluctuating velocity. The results show that the spectral peaks due to the fluctuating velocity near the rotor tip are mainly observed in the reverse flow region of higher flow rates than those in the peak pressure operating condition. However, no peak frequency presents near the rotor tip for near stall condition. Detailed wake flow just downstream of the rotor blade was also measured by the rotating hot-wire sensor. The peak frequency of a high velocity fluctuation due to Karman vortex shedding in the wake region is mainly observed at the higher flow rate condition than that in the design point.

Study on Discharge Electrode Design applied for Road Tunnel (터널용 전기집진시스템 개발을 위한 방전극 설계)

  • Kim, Jong-Ryul;Weon, Jong-Oung;Jang, Chun-Man
    • Proceedings of the SAREK Conference
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    • 2009.06a
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    • pp.1238-1243
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    • 2009
  • As Social Overhead Capital(SOC) has been expanded, the highway road construction has been accelerated and city road system has been more complicated. So, long road tunnels have been increased and traffic flow rate also has been raised. Accordingly, the exhausting gas of vehicle cars seriously deteriorates the tunnel inside air quality and driving view. In order to improve tunnel inside air quality, it is needed to introduce a compulsory ventilation system as well as natural ventilation mechanism. The former, that is, a special compulsory ventilation facility is very useful and helpful to prevent a tunnel of being contaminated by traffic in most case. In the case of obtaining clearer and longer driving view, the ventilation systems have to be considered in order to remove floating contaminants or exhaust gas from engines. In this paper, discharge electrode design technology will be discussed.

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Internal Flow Analysis for a 10 inch Ball Valve using Flow Similarity (유동상사를 이용한 10인치 볼밸브 내부유동 분석)

  • LEE, SANG-MOON;JANG, CHOON-MAN
    • Journal of Hydrogen and New Energy
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    • v.26 no.4
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    • pp.386-392
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    • 2015
  • Flow characteristics inside a 10 inch ball valve have been analyzed using three-dimensional numerical analysis and experiments. Continuity and three-dimensional Reynolds-averaged Navier-Stokes equations have been used as governing equations for the numerical analysis. The numerical model has been constructed through the grid dependency test and validation with the results of experiments to ensure reliability and numerical effectiveness. The shear stress transport (SST) model has been used as the turbulence closure. The experimental test-rig has been constructed to measure pressure, temperature and flow rate along the pipeline. Some valve opening angles have been tested to evaluate the flow characteristics inside the ball valve and pipeline. The results show that the rapid pressure variations is observed while the valve opening angle decreases, which caused by flow separation at the downstream of the ball valve.